INK RESERVOIR WITH A BIASING VALVE
An ink reservoir that contains ink and is detachably mountable to a printhead, the ink reservoir includes a free ink chamber for containing the ink; a valve assembly extending into the free ink chamber and including a first position for permitting ink to flow from the ink reservoir and a second position for stopping the flow of ink from the ink reservoir; and a wick that receives ink from the ink reservoir for transfer to the printhead.
The present invention relates generally to the field of ink reservoirs and, more particularly, to ink tanks for inkjet printers having a biasing valve for more efficiently permitting and stopping the flow of ink to a wick.
BACKGROUND OF THE INVENTIONAn inkjet printer typically includes one or more printheads and their corresponding ink supplies. A printhead includes an array of drop ejectors, each ejector consisting of an ink chamber, an ejecting actuator and a nozzle through which droplets of ink are ejected. The ejecting actuator may be one of various types, including a heater that vaporizes some of the ink in the chamber in order to propel a droplet out of the nozzle, or a piezoelectric device which changes the wall geometry of the chamber in order to generate a pressure wave that ejects a droplet. The droplets are typically directed toward paper or other recording medium in order to produce an image according to image data that is converted into electronic firing pulses for the drop ejectors as the print medium is moved relative to the printhead.
Ink is provided to the printhead through an inlet port of the printhead. In some printers, the corresponding ink supply can be located remotely from the printhead and connected to it, for example by tubing. Alternatively in other printers, an ink supply, also called an ink tank or ink reservoir, can be directly coupled to the printhead. For the case of ink tanks being mounted on the carriage of a carriage printer, the ink tank can be permanently mounted onto the printhead, so that the printhead needs to be replaced when the ink is depleted, or the ink tank can be detachably mounted onto the printhead, so that only the ink tank itself needs to be replaced when the ink tank is depleted. Carriage mounted ink tanks typically contain only enough ink for up to about several hundred prints. This is because the total mass of the carriage needs be limited, so that accelerations of the carriage at each end of the travel do not result in large forces that can shake the printer back and forth. As a result, users of carriage printers having detachably mounted ink tanks need to replace the ink tanks periodically, depending on their printing usage, typically several times per year. An ink tank design facilitating easy and clean installation of a detachable ink tank is beneficial.
One type of detachable ink tank includes a porous member (also called a wick or scavenger member) at the ink outlet port. The printhead inlet port can include a standpipe, for example, with a filter member at its inlet end. When the ink tank is mounted onto the printhead, the ink tank wick is held in contact with the filter member on the standpipe of the printhead inlet port. Once the printhead is primed so that liquid ink fills the various ink passageways between the wick and the nozzles on the printhead, capillary provide the force necessary to supply the ink as needed for printing. Such an ink tank facilitates easy and clean installation onto the printhead
In prior art ink tanks that include a wick, capillary media such as felt or foam is used to retain ink inside the ink tank and provide a slight negative ink pressure so that ink does not drip out of the nozzles of the printhead. This ink-retaining capillary media thus serves as a pressure regulator and provides ink to the wick at the ink outlet port.
It has been found that pigment particles in a pigmented ink can settle out in ink tank designs where ink is stored in a capillary media pressure regulator, partly due to the restriction of motion of pigment particles within the small passages of the capillary media, as described in more detail in U.S. patent application Ser. No. 12/139,533. Such settling of pigments particles, especially for larger pigment particles (e.g. larger than 30 nanometers), can result in defective images during the printing process. As a result, an ink tank using capillary media to store ink can lead to a limitation in pigment particle size that can be used. Such a limitation can be disadvantageous, because such larger particles can be beneficial for providing higher optical density in printed regions.
Consequently, a need exits for an ink tank that facilitates easy and clean installation onto the printhead, but that does not store ink in capillary media.
SUMMARY OF THE INVENTIONThe present invention is directed to overcoming one or more of the problems set forth above. Briefly summarized, according to one aspect of the invention, the invention resides an ink reservoir that contains ink and is detachably mountable to a printhead, the ink reservoir includes a free ink chamber for containing the ink; a valve assembly extending into the free ink chamber and including a first position for permitting ink to flow from the ink reservoir and a second position for stopping the flow of ink from the ink reservoir; and a wick that receives ink from the ink reservoir for transfer to the printhead.
While the specification concludes with claims particularly pointing out and distinctly claiming the subject matter of the present invention, it is believed that the invention will be better understood from the following description when taken in conjunction with the accompanying drawings, wherein:
Referring to
In the example shown in
In fluid communication with each nozzle array is a corresponding ink delivery pathway. Ink delivery pathway 122 is in fluid communication with the first nozzle array 120, and ink delivery pathway 132 is in fluid communication with the second nozzle array 130. Portions of ink delivery pathways 122 and 132 are shown in
Not shown in
Also shown in
As described below, one or more ink reservoirs (also called ink tanks herein) are detachably mountable in printhead chassis 250. In the bottom perspective view of
Printhead chassis 250 is mounted in carriage 200, and multi-chamber ink reservoir 262 and single-chamber ink reservoir 264 are mounted in the printhead chassis 250. When the ink reservoirs 262 and 264 are mounted in the printhead chassis 250, as in
A variety of rollers are used to advance the medium through the printer as shown schematically in the side view of
The motor that powers the paper advance rollers is not shown in
Toward the rear of the printer chassis 309, in this example, is located the electronics board 390, which includes cable connectors 392 for communicating via cables (not shown) to the printhead carriage 200 and from there to the printhead chassis 250. Also on the electronics board are typically mounted motor controllers for the carriage motor 380 and for the paper advance motor, a processor and/or other control electronics (shown schematically as controller 14 and image processing unit 15 in
A first embodiment of an ink reservoir according to the present invention is shown in the cross-sectional view
Valve assembly 281 in this embodiment includes a ball 282, a compression spring 283, a cap 284, and a sealing face 285. The ball 282 serves as a sealing member that is pressed by compression spring 283 against sealing face 285. The sealing face 285 is a circular rim disposed around the inner portion of the outlet port 272. The sealing face 285 is shaped so that it conforms to the shape of the ball 282 for firmly sealing the ball 282 against the sealing face 285 which, in this closed position, does not permit the ink to flow. Typically some elastic compliance is provided at the sealing interface between the sealing member (ball 282) and the sealing face 285 to provide a reliable seal. For example, ball 282 can be an elastomeric ball that can deform slightly by the pressure exerted by the compression spring 283, in order to seal against sealing face 285. One end of spring 283 is in contact with ball 282, while the opposite end of spring 283 pushes against cap 284. A portion of ball 282, which is opposite where spring 283 contacts ball 282, is in contact with wick 274 that is disposed at the outlet opening 273 of outlet port 272.
When valve assembly 281 is in the closed position, a space 286 exists between wick 274 and an inner face 287 of outlet port 272, as shown more clearly in the close-up view of
In the embodiment of
Wick 274, together with valve assembly 281 and free ink chamber 280 provide easy and clean installation of ink reservoir 264 onto printhead chassis 250 in embodiments of this invention. In addition, even though wick 274 is a porous member, ink is not stored in wick 274 but is constantly refreshed as new ink from the free ink chamber 280 flows through wick 274 printhead chassis 250. Because ink continues to flow through wick 274, pigment particles in a pigmented ink are not caused to settle out of the ink to an extent that printed image quality is thereby degraded, even if the size of the pigment particles is greater than 30 nanometers.
For embodiments of this invention where a pigmented ink is contained in free ink chamber 280, and the pigment particle size is greater than 30 nanometers, it is further advantageous for the pressure regulator in the ink tank to be a type that does not store ink in a capillary medium.
One type of pressure regulator that has been shown not to cause pigment particles to settle out to an extent that image quality is degraded is the pressure regulator described in U.S. patent application Ser. No. 12/139,533, and incorporated herein by reference. The pressure regulator described in U.S. patent application Ser. No. 12/139,533 and shown in
A second type of pressure regulator that can be used with the free ink chamber, valve assembly and wick of the present invention and not cause pigment particles to settle out to an extent that image quality is degraded includes a free ink chamber having a flexible wall member in contact with the free ink. As shown in
In summary, embodiments of the present invention have the advantages of providing clean and easy installation of the ink reservoir onto the printhead, providing an appropriate amount of negative ink pressure for proper operation of the printhead, and not causing pigment particles to settle out of the ink to an extent that image quality is degraded.
The invention has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.
PARTS LIST
- 10 Inkjet printer system
- 12 Image data source
- 14 Controller
- 15 Image processing unit
- 16 Electrical pulse source
- 18 First fluid source
- 19 Second fluid source
- 20 Recording medium
- 100 Inkjet printhead
- 110 Inkjet printhead die
- 111 Substrate
- 120 First nozzle array
- 121 Nozzle(s)
- 122 Ink delivery pathway (for first nozzle array)
- 130 Second nozzle array
- 131 Nozzle(s)
- 132 Ink delivery pathway (for second nozzle array)
- 181 Droplet(s) (ejected from first nozzle array)
- 182 Droplet(s) (ejected from second nozzle array)
- 200 Carriage
- 221 Enclosure
- 222 Hole
- 223 Vent
- 224 First capillary member
- 225 Second capillary member
- 231 Spring
- 232 Flexible wall
- 240 Standpipe
- 241 Region (for mounting multi-chamber ink reservoir)
- 242 Inlet port
- 243 Hole
- 244 Hole
- 245 End
- 246 Region (for mounting single chamber ink reservoir)
- 248 Inlet port
- 249 Partitioning wall
- 250 Printhead chassis
- 251 Printhead die
- 253 Nozzle array
- 254 Nozzle array direction
- 256 Encapsulant
- 257 Flex circuit
- 258 Connector board
- 261 Catch for ink tank latching mechanism
- 262 Multi-chamber ink reservoir (ink tank)
- 264 Single-chamber ink reservoir (ink tank)
- 271 Housing
- 272 Outlet port
- 273 Outlet opening
- 274 Wick
- 275 Back wall
- 276 Latching lever
- 278 Latch
- 279 Guide feature
- 280 Free ink chamber
- 281 Valve assembly
- 282 Ball
- 283 Compression spring
- 284 Cap
- 285 Sealing face
- 286 Space
- 287 Inner face
- 288 Plunger
- 289 O-ring
- 290 Flange
- 291 Stem
- 292 Extension
- 300 Printer chassis
- 302 Paper load entry direction
- 303 Print region
- 304 Media advance direction
- 305 Carriage scan direction
- 306 Right side of printer chassis
- 307 Left side of printer chassis
- 308 Front of printer chassis
- 309 Rear of printer chassis
- 310 Hole (for paper advance motor drive gear)
- 311 Feed roller gear
- 312 Feedroller
- 313 Forward rotation direction (of feed roller)
- 320 Pick-up roller
- 322 Turn roller
- 323 Idler roller
- 324 Discharge roller
- 325 Star wheel(s)
- 330 Maintenance station
- 370 Stack of media
- 371 Top piece of medium
- 380 Carriage motor
- 382 Carriage guide rail
- 383 Encoder fence
- 384 Belt
- 390 Printer electronics board
- 392 Cable connectors
Claims
1. An ink reservoir that contains ink and is detachably mountable to a printhead, the ink reservoir comprising:
- a free ink chamber for containing the ink;
- a valve assembly extending into the free ink chamber and including a first position for permitting ink to flow from the ink reservoir and a second position for stopping the flow of ink from the ink reservoir; and
- a wick that receives ink from the ink reservoir for transfer to the printhead.
2. The ink reservoir as in claim 1, wherein the wick is disposed in an outlet port for connection to the printhead.
3. The ink reservoir of claim 1, wherein the valve assembly comprises:
- a sealing member;
- a sealing face that receives the sealing member for stopping ink flow and that is a spaced apart relationship with the sealing member for permitting ink flow; and
- a compression spring that biases the sealing member into contact with the wick.
4. The ink reservoir of claim 3, wherein the sealing member comprises a ball.
5. The ink reservoir of claim 1, wherein the valve assembly comprises:
- a sealing member;
- a sealing face that receives the sealing member for stopping ink flow and that is a spaced apart relationship with the sealing member for permitting ink flow;
- a plunger in operative relation to the sealing member;
- a compression spring that biases the plunger into contact with the sealing member.
6. The ink reservoir as in claim 1, wherein the valve assembly provides a biasing force on the wick.
7. The ink reservoir as in claim 1 wherein the wick comprises a fibrous material.
8. The ink reservoir of claim 1 wherein the wick comprises a sintered material.
9. The ink reservoir of claim 1 further comprising a pressure regulator for providing a back pressure on the ink.
10. The ink reservoir of claim 9, wherein the pressure regulator comprises a pressure regulation chamber including a capillary media that is in fluidic contact with the ink in the free ink chamber.
11. The ink reservoir of claim 9, wherein the pressure regulator comprises:
- a flexible member in contact with free ink; and
- a spring in contact with the flexible member for providing pressure regulation.
12. The ink reservoir of claim 11, wherein the flexible member is a wall of an ink-containing bag.
13. The ink reservoir as in claim 1, wherein the ink is pigmented ink having a particle size greater than 30 nanometers.
14. An inkjet printhead assembly comprising:
- (a) an inkjet printhead including an ink inlet port; and
- (b) an ink reservoir that is detachably mountable to the printhead, the ink reservoir comprising: (i) a free ink chamber for containing ink; (ii) a valve assembly extending into the free ink chamber and including a first position for permitting ink to flow from the ink reservoir and a second position for stopping the flow of ink from the ink reservoir; (iii) an ink outlet port for receiving the ink from the valve assembly and transferring the ink to the ink inlet port of the printhead; and (iv) a wick disposed at the ink outlet port.
15. The inkjet printhead assembly of claim 14, the ink inlet port comprising a standpipe having an end, wherein the end of the standpipe is in contact with the wick when the ink reservoir is mounted on the ink inlet port of the printhead.
16. The inkjet printhead assembly of claim 15, wherein the ink inlet port further comprises a filter disposed at the end of the standpipe.
17. The inkjet printhead assembly as in claim 14, wherein the valve assembly provides a biasing force on the wick.
18. The inkjet printhead assembly of claim 17 further comprising a latching mechanism to hold the inkjet printhead and the ink reservoir together, wherein when the ink reservoir is mounted to the printhead and the latching mechanism is engaged, the ink inlet port contacts the wick which overcomes the biasing force of the valve assembly to displace the wick.
19. The inkjet printhead assembly of claim 18, wherein when the ink reservoir is mounted on the ink inlet port of the printhead and the latching mechanism is engaged, the valve assembly is forced open, thereby allowing ink to flow to the wick.
20. The inkjet printhead assembly of claim 14, wherein the valve assembly comprises:
- a sealing member;
- a sealing face that receives the sealing member for stopping ink flow and that is a spaced apart relationship with the sealing member for permitting ink flow; and
- a compression spring that biases the sealing member into contact with the wick.
21. The inkjet printhead assembly of claim 20, wherein the sealing member comprises a ball.
22. The inkjet printhead assembly of claim 14, wherein the valve assembly comprises:
- a sealing member;
- a sealing face that receives the sealing member for stopping ink flow and that is a spaced apart relationship with the sealing member for permitting ink flow;
- a plunger in operative relation with the sealing member;
- a compression spring that biases the plunger into contact with the sealing member.
23. The inkjet printhead assembly as in claim 14, wherein the wick comprises a fibrous material.
24. The inkjet printhead assembly of claim 14, wherein the wick comprises a sintered material.
25. The inkjet printhead assembly of claim 14 further comprising a pressure regulator for providing a back pressure on the ink.
26. The inkjet printhead assembly of claim 25, wherein the pressure regulator comprises a pressure regulation chamber including a capillary media that is in fluidic contact with the ink in the free ink chamber.
27. The inkjet printhead assembly of claim 25, wherein the pressure regulator comprises:
- a flexible member in contact with free ink; and
- a spring in contact with the flexible member for providing pressure regulation.
28. The inkjet printhead assembly of claim 27, wherein the flexible member is a wall of an ink-containing bag.
29. The inkjet printhead assembly as in claim 14, wherein the ink is pigmented ink having a particle size greater than 30 nanometers.
Type: Application
Filed: Jul 29, 2009
Publication Date: Feb 3, 2011
Inventor: Brian G. Price (Pittsford, NY)
Application Number: 12/511,326
International Classification: B41J 2/175 (20060101);